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水中氰化物一般采用蒸馏分离比色法测定。但由于灵敏度较低(0.020毫克/升)而不能测定氰含量为ppb级的水样。为解决此问题,在Frant提出的Ag_2S电极间接测定法基础上,Clyster和Adams建议以PbS沉淀形式过滤除去硫化物,用硝酸银电位滴定测定氰化物。此法可测氰含量低达1ppb的试样(1微克/升),但存在大量碘化物和硫代硫酸盐时干扰测定。Durst亦曾用气体渗透膜渗析分离技术获得了较高灵敏度(0.5微克/升,但所用装置较复杂。综合上述方法优点并克服缺点,在0.1NNaOH介质条件下,我们以高锰酸钾氧化强还原性有机物及S~(2-),I-等。
Cyanide in water is generally determined by distillation colorimetry. However, because of its low sensitivity (0.020 mg / l), it is not possible to determine water samples with a ppb cyanide content. In order to solve this problem, Crantster and Adams proposed to filter out sulfide by PbS precipitation based on Frant’s indirect method of Ag 2 S electrode determination. Cyanide was measured by silver nitrate potentiometric titration. This assay measures as little as 1 ppb of cyanide (1 μg / l), but in the presence of large amounts of iodide and thiosulfate interfere with the assay. Durst has also achieved higher sensitivity (0.5 μg / l) using gas permeation membrane dialysis and separation techniques, but with the more sophisticated equipment used. Combining the advantages of the method described above and overcoming the disadvantages, we oxidized potassium permanganate under 0.1 N NaOH medium Reducing organic compounds and S ~ (2 -), I- and so on.